Many modern electronic devices employ authentication techniques that involve a lock screen to control access to full functionality of the electronic device. These screenlock solutions reduce unauthorized access to the device. To unlock the device, the user may enter a correct personal identification number (PIN) (e.g., typically a four digit number), enter a correct password (e.g., a series of alphanumeric characters), pass a biometric scan (e.g., fingerprint swipe, face recognition, etc.), or manipulate or arrange items in a correct pattern or sequence (sometimes referred to as pattern unlock).
These solutions can have drawbacks. For instance, a picture of an authorized user may unlock a device that is protected with face recognition protection (also referred to as face unlock). As another example, PIN codes and passwords are difficult to remember, especially after a prolonged period of non-use or recently after changing the code or password. Pattern unlock may be circumvented by a recognizable residual smudge that is left of the face of the display.